Xantrex XW6048 Used as a UPS

mnittler

I would like to use the Xantrex XW6048 as backup power only for 240vac split phase circuit. Does anyone know what the transfer time is between between the power going out and the sub-panel being powered up by the XW6048? I plan on using the XW6048 to power critical circuits in a control room after a power failure until the backup generator can come on. Sell will be set to zero. The XW6048 will do all the battery charging and maintenance. Virtually what I need to happen is the XW6048 to act like a UPS. I need this unit to supply power to several PC's, PLC's, Video camera recorder system, and multiple control circuits until the power comes back on or the generator has time to start-up and produce power without giving any of the electronic items a glitch. 8)

halfcrazy

Re: Xantrex XW6048 Used as a UPS

The XW will do just that as long as there is utility power present it will close a relay and pass it through to your loads and float the batteries. as soon as utility power drops outside of the user set specs the relay opens powering the loads from the batteries it is a flawless switch from grid to battery and battery to grid.

mnittler

Re: Xantrex XW6048 Used as a UPS

Can you define flawless?
Will there be a delay before the relay kicks in and if so how many ms? I am looking at a PC and other electronic equipment connected to this sub-panel not getting the hiccups during the transition. Is the sub-panel continuously supplied by the XW6048 inverter instead of the incoming AC line power?

RCinFLA

Re: Xantrex XW6048 Used as a UPS

When the grid goes down it creates an overload on the inverter which is detected and relay connecting to grid is opened.

It typically happens is less then a cycle but worse case it may go as long as two cycles. It all depends where in the cycle the grid goes down and how the voltage profile of the grid drops out.

Most grid drop outs are the result of an overload somewhere is the area which causes the grid voltage to sag before a breaker opens. This gives some warning and results in XW opening up grid connect relay based on out of range low (210/105 vac) on grid voltage.

BB.

Re: Xantrex XW6048 Used as a UPS

I don't know specifically about the XW--But with regular computer room rack mounted UPS (APS and TripLite and others)--there are several types. One is like the XW which transfers on line fault...

That is the most efficient (simply uses the AC line power for loads and switches over to the inverter for off grid power).

And there is the continuous converter type. There the AC power "charges" the battery bank and the inverter pulls the DC power to provide local AC. No switching glitches/voltage sags at all--very clean power. However, less efficient (constant power conversion).

And you will find some hybrid units--Those fail over types with variable tap transformers to keep AC voltage relatively stable (and power losses down) until fail over function is needed.

And I have seen constant inverter types that run ~10% power from the inverter and 90% power from the line. More efficient, a bit cleaner power, plus if the inverter fails--it is detected immediately while AC power is good.

With regular industrial/commercial PC's--In the lab--fail over type inverters seemed to switch quick enough (1/2 AC cycle or less) that the computer never had any problem...

However, in real life, as a guess--I have seen about 1/10 real power failures would cause a one or more PC's to reboot (even when the UPS is working fine). I was never able to reproduce in a lab--Perhaps it is the way real power failures occur (arcs, glitch power before hand, sagging/surging power before failure, or something else that confused the fail over detection circuitry).

If this was a critical operation (chemical processing plant) or a place where fail over switching failures is not acceptable--I would probably not recommend a standard Hybrid solar inverter--they are not designed as a high reliability computer room UPS. Over he last few years of the failing economy, looking on EBay and other used equipment dealers--you probably can find some pretty nice used computer room UPS's.

If you wanted to combine solar / lower cost hardware as a UPS (such as the XW) where fail over failures are painful but not dangerous--You could use a XW or equivalent inverter/transfer switch setup and install smaller fail over or continuous converter UPS's on the few pieces of equipment that need 100% clean power (or even use battery powered laptop computers if they can do the processing for you).

My two cents.

-Bill

solar_dave

Re: Xantrex XW6048 Used as a UPS

I think much of the reboot scenarios are built into the power supply, I had a phone company computer room where I was the Unix admin with both HP and Sun servers in it. Any power line glitch cause the Suns to reboot, but the HPs ran happily through the event, even through the events that could be observed in the lighting.

I suspect the HP power supplies had a much more robust design. This was years ago, so take it with a grain of salt.

BB.

Re: Xantrex XW6048 Used as a UPS

A lot of time, it is just the amount of stored energy at the first state of the AC input to High Voltage DC (storage capacitor). Normally, it is designed to manage ~1/2 to 1 full cycle (at 60 or 50 Hz) of power line carry through--after that, the power supply output starts to droop.

-Bill

niel

Re: Xantrex XW6048 Used as a UPS

this is a tough question as i don't see how most relays are able to switch in a couple of cycles or less. the hysteresis of the relay and then the time in fall will surely take longer than that imho. speeds that are in the neighborhood of 1/120th to 1/30th of a second are usually achieved electronically without physical relays. if the relay in the inverter is of the electronic variety then i'll agree that it may be fast enough for the pcs and other pertinent items for switchover.

solar_dave

Re: Xantrex XW6048 Used as a UPS

BB. wrote: »

A lot of time, it is just the amount of stored energy at the first state of the AC input to High Voltage DC (storage capacitor). Normally, it is designed to manage ~1/2 to 1 full cycle (at 60 or 50 Hz) of power line carry through--after that, the power supply output starts to droop.

-Bill

HP must have put big caps in then, cause I saw those go a long time. Of course they were server class machines.

BB.

Re: Xantrex XW6048 Used as a UPS

Also, many times servers have 2 power supplies (N+1 redundancy) and they are not fully populated (use less power than max design)... It is not difficult to get multiple cycles of carry through without much extra costs.

-Bill

RCinFLA

Re: Xantrex XW6048 Used as a UPS

niel wrote: »

this is a tough question as i don't see how most relays are able to switch in a couple of cycles or less. the hysteresis of the relay and then the time in fall will surely take longer than that imho. speeds that are in the neighborhood of 1/120th to 1/30th of a second are usually achieved electronically without physical relays. if the relay in the inverter is of the electronic variety then i'll agree that it may be fast enough for the pcs and other pertinent items for switchover.

Specs on the power relay is 15 msec typ. release time. About one full cycle, assuming the contacts don't fuse together .

niel

Re: Xantrex XW6048 Used as a UPS

RCinFLA wrote: »

Specs on the power relay is 15 msec typ. release time. About one full cycle, assuming the contacts don't fuse together .

might work then and i stand corrected.;)

RCinFLA

Re: Xantrex XW6048 Used as a UPS

In almost twenty years using my old SW's inverters, on Florida Flicker and Flash grid, I have never had one of my PC's reset on a grid burp.

I have had one Directtv DVR reset on an outage.

It depends on particular power supply filter cap size and how much load there happens to be on power supply when outage occurs. A 500 watt power supply with a 70 watt load on it when outage hits will likely ride through five or more missed A.C. cycles.

mnittler

Re: Xantrex XW6048 Used as a UPS

I think you are correct in sayings that in most outages the power will be out of UL1741 spec long before the outage actually hits and the XW6048 would have already switched over to battery power. When I was doing some work with a co-gen plant once in working with the utility they informed us that during an outage the auto reclosures will close again in 7 cycles. We worked with them and finally after many arguments they finally got approval to increased the reclose time to 30 cycles to give us enough time to open the breakers as to not be out of sync when they reclosed again.
So which true sine wave inverter would stay in inverter mode 100% of the time running off of batteries? Instead of switching from line to inverter during a power failure.

Solar Guppy

Re: Xantrex XW6048 Used as a UPS

XW6048 can run the inverter 100%, I believe just use AC 2 ( normally the generator input ) for your AC input

BB.

Re: Xantrex XW6048 Used as a UPS

Any off-grid inverter will certainly run 100% of the time off of batteries.

The XW (and other similar hybrid inverters and inverter/chargers) certainly offer you more options (integrated charging + transfer switch).

The XW also supports running on AC2/Generator Input with a limited AC current--I.e., the inverter will supply energy in excess of the programed maximum current limit (AC2 input breaker rating?)--So it can supply surge power in excess of branch/generator ratings.

-Bill

System2

Re: Xantrex XW6048 Used as a UPS

I control 3 XW 6048s 1 I own personally.
The Xantrex XW series I would not use directly as a UPS
If the input is to erratic the XW tends to panic and can dump critical loads
and bring up a F code do the "---" or just have a blank display.

Now on that note there are ways to use the Xantrex XW as a UPS
but you have to prevent it from seeing outside power.

Use 1 XW unit to charge the batteries
and use another XW to do the inverter

Now you can use a dedicated charger and seperate inverter
for a much lower cost and get the same results

Pros
completely uninterruptible
completely isolated

Cons
in case of inverter failure you have no auto fall-back

In Short
The Xantrex XW will cover you from straight up power loss
but if the power fluctuates or is highly unstable there
is a chance that the XW will shutdown and disconnect critical loads

RCinFLA

Re: Xantrex XW6048 Used as a UPS

Skeil wrote: »

In Short
The Xantrex XW will cover you from straight up power loss
but if the power fluctuates or is highly unstable there
is a chance that the XW will shutdown and disconnect critical loads

Never seen that. It may be associated with having paralleled XW's. Later SW revs may be more stable in this paralleling aspect.

XW will release from grid at first sign of a glitch. It takes several minutes to reconnect and evaluates grid stability before reconnecting.

There are two modes of backup. One runs the inverter all the time in parallel with grid. The other has inverter shut down but grid sync is kept track of to allow for immediate inverter activation. It does take a little longer, several cycles, to fire up and stablize the inverter.

If you want the best UPS performance the inverter should be kept running in parallel all the time. It will cost you maybe an extra 10-15 watts of continuous power to keep the inverter running.

sideshow

Re: Xantrex XW6048 Used as a UPS

I'm wandering did you ever implement this solution and did it work well. I fine myself in the same situation, and am considering implementing it.

Thanks

t00ls

I have an older 4548 xw...I have had power outages here 2 times

I didnt even notice the power was out everywhere.....I have 2000 watts of solar and auto start for the generator when battery voltage gets too low

from what I read you have everything you need to do whole home backup power.....you bring grid power in on the ac in and inverter out to the home.....grid power will pass through untill there is an outage , then the relay switches without interruptions long as you are not pulling more loads than what the inverter can handle

if you want to sell to the grid, first you need a contract with the utility company or they will come shut your meter off

I dont sell to the grid.....instead I set my sell amps to 0 (zero) and as long as I dont need more power than the solar is providing ...it just stops the meter from turning.....

this way I dont need a contract

dang...just saw the date....guess I'm late to the party